1. Field of the Invention
The present invention relates to an apparatus and a method for non-network channel scanning. More particularly, the present invention relates to an apparatus and a method for non-network channel scanning in a digital video broadcasting system.
2. Description of the Related Art
From among digital broadcast systems, a Digital Video Broadcasting (DVB) system is widely used.
The DVB system employs two scanning schemes for searching for available service and Service Information (SI), and for storing the available service and SI in a database located in a non-volatile memory.
A first scheme is a network scanning scheme, which is used in standards for a satellite broadcast and cable broadcast, an entire network of which is managed by broadcast providers. In the first scheme, a preset channel (i.e., a Transport Stream (TS) in which services are multiplexed, or a broadcast stream corresponding to a physical frequency) carries SI of another channel, so that it is possible to obtain SI of all channels from one channel, which enables convenient scanning. Further, since one broadcast provider manages the entire network, it is possible to scan the entire network according to the same scanning scheme.
A second scheme is a non-network scanning scheme, in which multiple broadcast providers use different channels of the same network without a separate service provider managing the entire network. The non-network scanning scheme is used for terrestrial and handheld broadcast standards. In the non-network scanning scheme, for scanning, it is required to obtain information (i.e., SI) from each channel. Further, since the non-network scanning scheme mainly uses a Multi Frequency Network (MFN), a physical frequency of the service is different according to the area, and the same service may be repeatedly scanned in multiple frequencies in an MFN boundary area. Further, when different services have the same Logical Channel Number (LCN), it may be impossible to store the service.
FIG. 1 illustrates an example of a service in an MFN boundary area according to the related art.
Table 1 below shows an example of a result of scanning according to a scanning standard, to which the LCN is applied, in a C cell 120 of FIG. 1, which is an MFN boundary area.
TABLE 1ServiceServiceNumberNameFrequencyProblem1AAA570 MHz2DDD570 MHz1. Due to different LCNs, both services3DEF578 MHzshould be stored although they are thesame service.4FFF586 MHz2. Due to the same LCN, HHH is notstored.12OOO586 MHz2. Due to no LCN, PPP is not stored.
Table 2 below shows a result of the scanning in an A cell 100 and a B cell 110.
TABLE 2Service IDService NameLCNFrequencyA cell0x0080AAA1570 MHz0x0130DDD2570 MHz0x0282FFF4586 MHz0x0681OOO12586 MHzB cell0x0080AAA1578 MHz0x0130DEE3578 MHz0x0375HHH4592 MHz0x0682PPPNone592 MHz
Hereinafter, a result of scanning in the C cell 120, which is an MFN boundary area, will be discussed.
When a service Identifier (ID) is 0x0080, the services are scanned through two frequencies although they are the same. That is, the service is scanned through 570 MHz in an area corresponding to the A cell 100, and is scanned through 578 MHz in an area corresponding to the B cell 110. However, since the service in the A cell 100 and the B cell 110 have the same LCN, based on an assumption that the service scanned first is maintained, only the service with the frequency of 570 MHz is stored from among the two normal services as shown in Table 1.
When the service ID is 0x0130, the services have the same service ID and different LCNs. In this case, both of the services are stored in Table 1. However, a problem exists in that both DDD and DEE are stored.
Further, when the services have service IDs of 0x0282 and 0x0375, the services are different but have the same LCN of 4. Therefore, based on an assumption that the service scanned first is maintained, HHH is not stored. That is, a problem exists in that one of the two services is not stored.
Further, when the service has a service ID of 0x0681, since the LCN of the service is 12 and the service name is OOO, the service is normally stored. However, when the service has a service ID of 0x0682, since the service does not have an LCN, the service is not stored.
Based on the above-described problems, a scanning scheme for addressing the problems of each country is temporarily applied to the country. As a result, application of different scanning schemes to different countries increases maintenance expenses.
Meanwhile, the non-network scanning includes automatic scanning, which scans an entire frequency table of a country, and manual scanning, which scans a particular frequency. In general, most countries use the LCN. The LCN is a specific service number allocated to each service. In a country that does not use the LCN, numbers are sequentially allocated to the services from number 1.
A scanning scheme in a standard using the LCN is described below.
1. An automatic scanning scheme in a standard using the LCN is as follows:                1) All services stored in a database are deleted.        2) Scanning is performed until the scanning is completed for all the frequencies, while the services scanned in each frequency are stored in a memory with LCNs as service numbers.        3) The services stored in the memory are stored in a database.        
2. A manual scanning scheme in a standard using the LCN is as follows:                1) Services of the frequency to be scanned from among the services already stored in a database are deleted.        2) The scanned services are stored in a memory with LCNs as service numbers.        3) The services stored in the memory are stored in a database.        
3. An automatic scanning scheme in a standard that does not use the LCN is as follows:                1) All services stored in a database are deleted.        2) Scanning is performed until the scanning is completed for all the frequencies, while the services scanned in each frequency are stored in a memory with LCNs as service numbers.        3) The services stored in the memory are stored in a database.        
4. A manual scanning scheme in a standard that does not use the LCN is as follows:                1) Services of the frequency to be scanned from among the services already stored in a database are deleted.        2) The scanned services are stored in a memory.        3) The services stored in the memory are stored in a database while sequentially matching the services to service numbers omitted in the database or numbers from a number next to the last number existing in the database.        
As described above, when it is necessary to apply different scanning schemes according to whether the LCN is used, different applications are necessary according to the countries. Further, when a service that does not have an LCN exists in the standard using the LCN, scanning is impossible although scanning may be necessary based on inaccurate information of SI data in a field.
Therefore, a need exists for a scanning method in which scanning is possible regardless of LCN use standards.